package leetcode100;

public class lc047 {
    public static void main(String[] args) {
        int n = 3;
        int res = new lc047().numTrees(n);
        System.out.println("res = " + res);
    }

    public int numTrees(int n) {

        int[] dp = new int[n+1];

        dp[0] = 1;
        dp[1] = 1;

        for (int i = 2; i <=n ; i++) {
            for (int j = 1; j <=i ; j++) {
                dp[i]+=dp[j-1]*dp[i-j];
            }
        }


        return dp[n];
    }
}
